Government documents reveal close to a dozen metro and heavy rail stations have been mapped out for around Western Sydney.
Places in the city's north-west and south-west were flagged in the documents got by the state opposition.
Opposition Leader Kellie Sloane says Sydneysiders will get another metro if they elect a Coalition government.
In the north-west, the potential stations include Emerton, Bidwell, Marsden Park and Schofields.
In the south-west, they include suburbs like Maryland, Pondicherry and Oran Park.
The map was got by the state opposition, as part of a parliamentary order for government documents.
The Minns government has already set aside $40 million for a business case to assess the feasibility of extending the Western Sydney Airport Metro in a northerly direction from St Marys to Tallawong, via Marsden Park and Schofields.
The federal and state governments have also jointly committed $100 million for another business case to assess southerly rail extensions, linking the new airport with Campbelltown and Leppington.
While business cases themselves remain confidential, the map released to the opposition sheds new light on the potential routes each extension could take.
Shadow Transport Minister Natalie Ward said she was "excited" to have uncovered the map.
"We've uncovered the document that's been sitting on [Transport Minister] John Graham's desk for months."
The map shows a northerly extension from St Marys to Tallawong, where the existing metro now terminates.
While she before vowed to "progress" a new metro in the city's south-west, Ms Sloane said the opposition was still open to the northern extension between St Marys and Tallawong.